Horizontally acting hydropneumatic buffer



Aug.25,197o v 3,525,449

HORIZONTALLY ACTING HYDROPNEUMATIC BUFFER Filed Feb. l5, 1968 A. L.'zANow W W Q\.u` M M Nm m A m L. W RPS NAW W n W MUM W MJ v... A WQ\ KNKwww mwN. -m MN. \w Nw NN QN. \DN N 5 5 5 @mw/N N .I `W\ ,N 5 I|\/Wmllmmu |Hwm| 5i/4| /w wmww "Q NN m\ MNA@ 1i i S s ww Q S QN w Q E Nw Q\N NN al mw MS, A .XN my \f\ \w\v\\\\\\\\vw 5&5 551V/ Mw L M\\` |I||\\\\\WW|INHIW1IWN1. mw N\\ M .|i JR M5 Aww H @w Nmmv MQS IE BY W UnitedStates Patent O 3,525,449 HORIZONTALLY ACTING HYDROPNEUMATIC BUFFERAndrey L. Zanow, Cleveland, Ohio, assignor to Midland- Ross Corporation,Cleveland, Ohio, a corporation of Ohio Filed Feb. 15, 1968, Ser. No.705,796 Int. Cl. B61g 9/02, 9/12 U.S. Cl. 213-43 4 Claims ABSTRACT OFTHE DISCLOSURE DESCRIPTION OF THE INVENTION The present invention isconcerned in particular with heavy-duty buffers which may be placed inthe underframe of a railway car to absorb forces imposed on the couplersof the car as the result of coupling or over-thetrack train operations.While buffers of the type herein described may be used in the manner ofcoventional draft gears functioning within a xed pocket within thecenter sill of t-he car, they are adapted especially for use in cars ofthe sliding sill type wherein the buffer is used to connect the elogatesliding sill which extends through the car from coupler to coupler inresilient relation with the car body.

An important object of the invention is to provide buifers capable ofhigh energy dissipation for use, e.g., on railway cars, and especiallybuiTers which yield high capacities in relation to the space in arailway car underframe which may be allotted to the buffer.

Another object is to utilize hydropneumatic principles in achieving theforegoing object and to provide a hydropneumatic buffer in which ahydraulic cylinder is automatically purged of gas during reciprocationof a piston assembly thereof.

A further object is to provide a hydropneumatic buffer based upon adesign wherein two pistons or the equivalent thereof, arranged inrelatively iixed, spaced, tandem relationship, traverse the main workingcylinder.

These and other objects are achieved in a single-acting hydraulic bufferhaving a cylinder enclosed at one end by a head and an opening at theother end traversed by an assembly including a piston rod and a pair ofpistons or equivalent members xed to the rod in axially spaced, tandemrelationship. The buffer also includes a reservoir of sufficientcapacity to contain all uid removed from the cylinder by the piston andpiston rod assembly in addition to space for the storage of air placedunder compression by liquid forced into the reservoir from the cylinder,and to provide space for spare liquid.

The present invention is concerned particularly with duct means at leastpartially contained within the head with one terminus in communicationwith the region swept by the inner piston and having its other terminusin an extreme lower part of the reservoir. The latter terminus isarranged relative to other parts of the buier to assure that all liquidreturning to the cylinder from the reservoir passes through such lowerterminus of the duct. In a preferred embodiment, the duct means withinthe Patented Aug. 25, 1970 rice head has the first named terminusopening into an extreme upper part of the region swept by the innerpiston adjacent the junction of the cylinder and the head.

In the drawing with respect to which the invention is described:

FIG. l is a cross sectional view taken along the longitudinal axis of abuffer of relatively simple construction;

FIG. 2 is a cross sectional view taken along a longitudinal axis of abuffer having a liquid-gas reservoir in separated but uid communicatingrelation with a cylinder and piston assembly of the buffer;

FIG. 3 is a cross sectional view taken along a longitudinal axis of abuffer which includes a metering tube for controrlling passage of liquidfrom the cylinder into the reservoir thereof and another duct system forpassing of liquid from the reservoir into the cylinder;

FIG. 4 is a cross sectional view along line IV-IV of FIG. 3 takentransversely of the longitudinal axis;

FIG. 5 is an enlarged View in cross section of a portion of FIG. 1relating to valve mechanism in the cylinder head;

FIG. 6 is a cross sectional view taken along the longitudinal axis ofanother modified buffer;

FIG. 7 is a transverse cross sectional view of the buffer of FIG. 6taken along line VII-VII;

FIG. 8 is a transverse cross sectional view of the buer of FIG. 6 takenalong line VIII-VIII;

FIG. 9 is a cross sectional view taken along the longitudinal axis ofstill another modified buffer having a reservoir which surrounds merelya part of the length of the cylinder and communicates with the cylinderpartly through the cylinder head and partly through a tube; and

FIG. l0 is a transverse cross sectional View of the buier of FIG. 8taken along line X-X of that figure.

Of the various embodiments herein disclosed, FIG. 1 illustrates thesimplest form of the invention in which a relatively short-bodied buffer5 comprises a cylinder formed by a tubular wall 6 and a head 7 attachedto the wall 6 by means, such as welding at 8. The buler furthercomprises an assembly 9 which includes a piston rod 10 and a cylindricalmember 11 secured thereto by a bolt 12 forming the equivalent of twopistons in axiallyspaced, tandem, fixed relationship. The member 11oomprises axially-spaced enlarged piston portions 11a and 11b whichfunction as two pistons in tandem relation to provide bearing areas onthe inner surface of the wall 6 assuring the alignment of the piston andpiston rod assembly 9 with the cylinder in the presence of substantiallymisaligning forces which are possible in railway car use.

As the buffer of FIG. l embodies an integral reservoir, a storage region14 for liquid and gas is enclosed by the wall 6, another cylindricalwall 15 shown welded at 16 to an annular shoulder of the head 7, and aflange member 18 secured adjacent the open end of the cylinder wall 64by means such as bolts 19 as shown. The ange 18 is grooved at 20 and 21to accommodate sealing material in engagement with surfaces of the walls6 and 15 in forming the reservoir region 14. The piston rod has anannular shoulder 22 formed by a difference in diameters of the rod whichcooperates with an outward end surface of the member 11 to confine aresilient sealing ring 23 and a rigid, nonresilient support ring 24 infixed relationship with the piston rod assembly 9, and the ring 23, andin frictional sealing relation with both the assembly 9 and cylinderwall 6.

As an essential feature of the invention, the head 7 provides duct meansbetween a lower extremity of the reservoir at 25 and the region withinthe cylinder swept by the inner surface 26 of the piston and piston rodassembly 9. In the embodiment of FIG. l, such duct means connects theextreme lower portion of the reservoir and extreme upper portion of theswept cylinder region. As shown, the duct means consists of a verticalbore 27 terminating in a smaller diameter section 28, and anintersecting horizontal bore 29 connecting the swept cylinder region andthe bore section 28. An adjustable plug 31 is provided .along a threadedportion of the bore 29 which may be adjusted with reference to a seat 32formed by head structure within the bore 29 to obtain different liquidpressure ranges resisting the closure of the buffer. The duct means justdescribed functions in controlling the rate of passage of liquid betweenthe reservoir and the cylinder in both closing and return strokes of thepiston assembly since this is the only passageway through which uidexchange is effected between the cylinder and the reservoir.

In the embodiment of FIG. 1, as in the other embodiments to be describedherein below, the buffer is oriented with its longitudinal axis alignedhorizontally or within normal practical tilting ranges of such buffersin railway use. Such buffers, in order to practice the invention, mustbe oriented with junction of the reservoir with the duct means forreturning liquid from the reservoir to the cylinder at approximately thelowest portion of the reservoir.

FIG. 2 illustrates a buifer 35 having a piston, cylinder, and headarrangement similar to that of FIG. 1. It differs essentially in thelocation of the reservoir 36, and structure for accommodating a spring37 which assists a gas under compression in the upper portion of storagespace of the reservoir 36 in returning the piston and piston rodassembly 38 to its most outward position relative to a cylindrical wall41. Similarly to the earlier described embodiment of FIG. 1, the buier35 has a cylindrically shaped member 42 fitting over the inner end ofthe piston rod 43 comprising spaced tandem piston portions 44 and 45. Amoving seal xed to the piston rod at 46 is provided on the assembly 38as in the manner described with respect to the 'buffer 5. The member 42and the piston rod are open along the axis of the cylinder to provide achamber 51 for accommodating the return spring 37. A guide rod 53 iixedto the head 54 of the cylinder in concentric relation with the cylinderaxis maintains the spring in proper registry with the region 51 duringcompression strokes of the buffer.

The important significance of FIG. 2 is that it illustrates that thereservoir 36 may be separately located from the cylinder and assembly 38as effective storage for the oil or other liquid which passes to andfrom the portion of the cylinder swept by the innermost surface 55 ofthe piston and piston rod assembly. As shown, the reservoir is providedwith a lill opening 58 deiined in part by tubular boss 59 threaded alongthe upper portion thereof for receiving a threaded plug 61. Boss 59terminates at a desired level for liquid at the most outward position ofthe assembly 38. That is to say, when a liquid is poured into thereservoir through the exposed opening 58, air is trapped above the lowerextremity of the boss 59 and no more liquid can be poured into thereservoir. Additional air or other gas may be forced into the reservoirthrough a valve 62 of the type such as that commonly used on automotivetires.

FIGS. 3 and 4 illustrate a buifer 65 of relatively longtravel capacityadapting it for use in car underframe structure commonly known as asliding-sill rigging. In this embodiment, the basic arrangement ofreservoir, cylinder, and piston and piston rod assembly is maintainedwith, however, material modication in the mode of securing buffercomponents together, and in duct structure for passing liquid betweenthe reservoir and the cylinder during compression and expansion strokesof the buffer. The tandem arranged piston means characteristic of theinvention comprises, in this instance, a cup shaped piston 66 secured tothe end of the piston rod 67 and a sleeve 68 secured to an intermediateportion of the piston rod. The outer diameter of the sleeve 68 isannularly recessed for a sealing material 71 held in place by rigid ringstructure 72 seated against a shoulder of the piston rod created bydifferences in diameter of the rod.

The essential feature of the buffer 65 illustrated by FIGS. 3, 4, and 5is in the construction of the two-piece head 75 comprising an annularblock 76, a cylinder insert 77, and elements of valve mechanismincluding a plug 79, the spring 81, and a cartridge 82. The buier 65differs from the others primarily in the structure for passing liquidbetween that portion of the cylinder swept by the piston 66 and thefluid storage space 84 of the reservoir as formed by the cylinder wall85, the cylindrical outer reservoir wall 86, the head 75, and a collar87 shown welded to the Wall 86.

Attached to the insert 77 of the head is a metering tube 88 accommodatedby a suitable bore 89 extending through a substantial inward portion ofthe piston rod 67 and necessarily through the piston 66. The tube 88 issecured as by welding to the insert and extends into a complementarybore of the insert in concentric coaxial relation with the buier axisMN. The insert 77 forms an annular coaxially extending boss 91 extendinginto a complementary recess of the block 76. This recess terminates inan axially-outward threaded bore for receiving the plug 79. The central`bore of the insert 77 has an axially outward portion 93 complementaryto the outer surface of the cartridge 82 along which the cartridge maymove away from the end of the metering tube 88 in response to anincrease in pressure caused by inward movement of the piston and pistonrod assembly. Such movement of the cartridge is resisted only slightlyby the spring 81 since the function of the latter is to return thecartridge to a position against the end of the tube 88 as soon as thepiston rod assembly ceases to move in a direction toward the head andthere is a consequent drop in the internal pressure of the cylinder toequilibrium with that of the reservoir. As shown, the plug 79 provides aseat for the spring 81 and a central pin-like portion 94 functioning asa guide as it moves into telescopic relation with the cartridge 82 alongits central bore.

Movement of the cartridge away from the end surface of the tube 88permits liquid to escape into the open space provided around the head ofthe cartridge by an intermediate portion 96 of the insert bore. Thehollow region thus provided is contiguous with a duct 97 which extendsdownwardly within insert 77 and terminates at 98 adjacent to, but inclearance with, the outer wall 86 of the reservoir. As shown in FIG. 4the buffer 65 has means, such as four lugs 99 adapting it to lit acompartment of square cross section in which it is prevented fromrotating about its axis. The buffer is thus iixed in a position in whichthe lower terminus of the duct 97 is maintained at approximately thelowest point in the reservoir.

At the fully shortened or buried condition of the buffer 65, the oillevel in the reservoir space 84 will |be at its highest and the airabove the oil will be at a maximum pressure. Hence, with cessation ofbutling force acting on the buffer, compressed air or other gas in thereservoir space 84 forces liquid back in to the working cylinder throughthe duct 97, bore portion 96, and a passageway having a lower section101 of small diameter for metering the rate of oil returning to`cylinder as the piston 66 moves outwardly. The passageway has an uppersection 102 in which is received a ball 103. This ball seats at ajunction of the sections 101, 102 to function as a check valve, mildlypreloaded as by gravity, preventing passage through the passagewayduring shortening of the buffer but unseating during expansion of thebuffer to permit passage of liquid into the cylinder. The seat for theball 103 may be formed as disclosed below with respect to the embodimentof FIG. 6` to permit slight leakage during an inward stroke to enablepurging of air from the space swept by the piston 66. The cartridge 82seats against the end of the tube 88 and thus prevents passage of liquidinto the cylinder by way of the tube 88.

The buier is initially loaded with suicient liquid to maintain the levelthereof within reservoir at a discrete level 'above the lower entranceto the duct 97 to avoid the possible entrance of air thereinto.

FIG. 6 illustrates 'a type of hydropneumatic buffer adapted for mountingwithin a sliding sill and cushioning it with respect to fixed carunderframe structure, such as a center sill. As basic features found inearlier described embodiments, the butler 110* has a cylindrical Wall111 and a head 112 defining a cylinder in which a piston assembly 114 isreciprocable in telescoping relationship with a metering t-ube 115rlixed to the head 112 in coaxial relation therewith. As shown, themetering tube extends within a coaxial bore 116 of the head stoppered atits outer end by a plug 117.

The assembly 114 comprises a piston rod 121 and pis.- tons 122 and 123attached thereto in spaced tandem relationship. To prevent leakage fromthe working cylinder, an annular resilient seal 125 is secured betweenthe piston 123 and a supporting ring 126. The piston rod is showndrilled with a passageway 128 which relieves any pressure within thecylinder in the annular region 129 formed by spacing of pistons 122 and123. The duct 128 has a check valve 131 which allows relief of pressurein the region 129 higher than that in a bore 132 of the piston rod foraccommodating the tube 115. The check valve 131 is oriented to preventequalization of pressure when the pressure in bore 132 is higher than inthe region 129. Another passageway 134 from the perimeter of the piston122 to the bore 132 drains off high pressure liquid around the piston tothe bore to prevent transmission of excessive liquid and pressure to aresilient seal ring 135 in the periphery of the piston 122 and passageto the region 129'.

The embodiment of FIGS. 6, 7`, and 8 is especially notable for a duct138 for completing the communication channel between the region withinthe working cylinder swept by the front face 141 of the piston 122 andthe generally annular reservoir 142 through the tube 115 and the bore116 contiguous therewith. The reservoir is bounded and defined by thehead 112, an outer cylindrical wall 144, the cylinder wall 111, and thesleeve 145 fitting between walls 111 and 144 adjacent to the open end ofthe working cylinder.

As shown, the wall 111 is secured to the head 112 by Welding at 147. Thesleeve 145 is secured to the outer surface of the wall 111 and in turnholds the wall 144 in its proper position. Any leakage from thereservoir is prevented by resilient seals 151 and 152. A ilange ring 153bolted to the sleeve 145 functions as a stop for the assembly 114 inoutward or return movements.

It will be noted that the Wall 111 is secured to the head so as to leavea slight clearance 155 between the end of the wall 111 and the innerhead surface 156. A passageway 139 extends in a right langle path fromthe surface 156 at a point in longitudinal alignment with the endsurface of the wall 111. The clearance 155 functions as a duct for thepassage of fluid from the cylinder into duct 139. This duct has a shorthorizontal counter-bored leg 139a which together with a ball 154 forms acheck valve preventing the passage of liquid through the duct 139 duringa closing stroke, i.e., a stroke in which the assembly 114 moves towardthe head 112. However, at this time, liquid moves from the cylinderprimarily through apertures 157 in the metering tube and through theduct 138 past the ball check valve 158 and into the region 142 of thereservoir. At cessation of buffer-shortening force, the air compressedwithin the upper part of the region 142 causes the buffer to expand inthe longitudinal direction, i.e., to drive the assembly 114 outward oraway from the head 112. When such movement of the assembly occurs, thecheck valve in the passageway 1319a opens and liquid is forced throughthe duct 139 from approximately the lowest portion of the region 142 andinto the extreme upper portion of the cylinder. The relative sizes ofthe duct portions 138 and 139 indicate that liquid is permitted toreturn to the cylinder in a relatively small stream which results in aslow and controlled rate of longitudinal expansion of the bulfer.

As shown in FIG. 8, various elements of the butler are of circularrelatively-concentric contour but the portion of the head adjacent itsend surface 116 may be of rectangular or square contour, or othercontours to fit a buffer-receiving compartment so that the buffer may besupported against rotation about its longitudinal axis. Preferably, thecheck valve seat for the ball 154 is arranged to allow slight leakageduring a closing stroke of the buffer in order that any air or other gascollected in the top of the cylinder will have an opportunity to bedischarged into the reservoir.

FIGS. 9 and 10 depict a long-stroke tbulfei of the type suitable for usein sliding-still type cars. An essential feature of this embodiment isthe provision of a casing 'which encloses only a portion of thecylindrical wall 166 in spaced remote relation with a head 167 of thebuffer, i.e., a portion of the wall 166 adjacent it open end. Thereservoir region 168 formed by the casing 165 and the cylindrical wallis connected `by a duct, such as a tube 171. Such an arrangement ispractical in constructing buffers of extra length since it is generallyexpensive and unnecessary to make the reservoir coextensive with thefull length of the cylinder. For example, the cylindrical wall 166 isconnected to the head 167 by a simple weld and the casing 165 issupported along machined outer surfaces of the cylinder without anygreat need for perfect concentricity of a casing with the axis OP of thepiston and piston-rod assembly 174. -In a buffer designed according toFIGS. 9 and 10, the head 167 provides a passageway or duct 176 whichextends from a lower horizontal bore 177 in the extreme lower portion ofthe head complementary to the outer surface of the tube 177, to a bore178 in coaxial relation with a metering tube 179 or axis OP. The duct176 extends upwardly from the axis OP in smaller cross section and thenhorizontally as a section 181 into the extreme upper portion of theregion 182 swept by the inner surface 183 of the piston and piston-rodassembly 174. In common with other above described embodiments, theassembly 174 includes two axially-spaced pistons 185 and 1-86.

In closing strokes, liquid is forced from the region 182 into thereservoir simultaneously through both duct sections 178 and I181 to theduct 176 and thence through the tube 171 into the main storage region168i. The tube 171 may be considered in a minor degree as reservoirspace for liquid transferred into and out of the cylinder region 182.

As any air present in the cylinder tends to collect in the upper portionthereof, a closing stroke of the buffer purges air from the cylinderoutwardly through the duct section 181 and ultimately to the upperportion of the reservoir region 168. During a return stroke, i.e., whenthe assembly 174 moves outwardly of the working cylinder underpropulsion of, e.g., a spring (not shown) acting between the casing 165and a bearing block 188, and/or compressed air stored within the region.168', liquid moves through the duct 176 and through both the ductsection 181 and the metering tube 179. In manner consistent with earlierdescribed embodiments, liquid free from any entrapped air is forced fromthe extreme lower portion of the reservoir into the cylinder.

However, it is to be observed that all buffers are selfpriming. That isto say, even if, e.g., the Working chamber formed by elements 85, 66 and77 is left purposely void of liquid at an expanded condition, then upona single, or, at the most, only a few shortenings and reexpansions ofthe buffer, the air will be purged from the chamber and, because of thefeatures of the passageways described, replaced by liquid. This holdstrue for all embodiments described herein unless the reserve oil supplyhas been depleted, i.e., it has nearly reached the level of the lowerterminus of e.g., the duct 97. Furthermore, the pressure required topump the liquid intoy the chamber dened, e.g., by elements 85, 66, 77,depends upon the specific weight of the fluid, and is normally small,except for the case of embodiment shown in FIG. 2 wherein the reservoir33 is located very much below the buffer, requiring a proportional riseof pressure. A higher pressure is desirable only to obtain expansion ofthe buffer.

While the buffers described are ordinarily operated with sealedreservoirs, the reservoirs may be connected with an air supply (notshown) regulated to a constant supply pressure at which air passes intothe reservoir, if it drops below a desired minimum.

What is claimed is:

1. A hydropneumatic burer having a longitudinal axis along which thebuffer contracts and expands, and a bottom portion in radial relationwith said axis, said buffer intended for use with said axis alignedgenerally horizontally with said bottom portion directly under saidaxis, said buler comprising:

a cylinder concentric to said axis and having a central opening at anouter end thereof;

a cylinder head enclosing the inner end of the cylinder;

an assembly adapted to reciprocate within the cylinder as a unitcomprising a piston rod extending outwardly through said opening andpiston means in ixed relation to said rod conforming to the innercylindrical surface of the cylinder in sealed slidable relationtherewith;

a reservoir providing storage space for liquid and gas substantiallyexceeding the volume of said cylinder swept by the inward face of thepiston means, and an additional predetermined volume for the storage ofgas above the liquid received from the cylinder when said piston meansoccupies its inwardmost position;

stop means for limiting travel of said assembly to an operative ambitretaining the piston means within the cylinder;

first duct means in said head communicating with said swept region andextending to the lowest extremity of said reservoir space;

second duct means in said head in communication with said swept regionand connecting with said reservoir space; and

check valve means for controlling passage of fluid through said secondduct means arranged to open during an inward stroke of said assembly;

said yiirst duct means being separate from said second duct means andconnecting with an upper extremity of said swept region.

2. The buffer of claim 1 comprising:

check valve means in said lirst duct means oriented for opening duringan outward stroke and constructed 8 for a slight leakage of iluidtherethrough during an inward stroke.

3. A hydropnuematic buffer having a longitudinal axis along which thebuer contracts and expands, and a bottom portion in radial relation withsaid axis, said butler intended for use with said axis aligned generallyhorizontally with said bottom portion directly under said axis, saidbuffer comprising:

a cylinder concentric to said axis and having a central opening at anouter end thereof;

a cylinder head enclosing the inner end of the cylinder;

an assembly adapted to reciprocate within the cylinder as a unitcomprising a piston rod extending outwardly through said opening andpiston means in ixed relation to said rod conforming to the innercylindrical surface of the cylinder in sealed slidable relationtherewith;

a reservoir providing storage space for liquid and gas substantiallyexceeding the volume of said cylinder swept by the inward face of thepiston means, and an additional predetermined volume for the storage ofgas above the liquid received from the cylinder when said piston meansoccupies its inwardmost position;

stop means for limiting travel of said assembly to an operative ambitretaining the piston means Within the cylinder;

duct means in said head communicating with said swept region andextending to the lowest extremity of said reservoir space, said ductmeans having one portion opening into an extreme upper portion of saidswept region and a second portion opening into said region at a lowerlevel;

check valve-means in said one portion oriented to close during thepassage of liquid from said region to the reservoir through said secondportion; and

check valve means in said second portion oriented for closing duringpassage of liquid from the reservoir to said region through said oneportion.

4. The buffer of claim 3 wherein said check valve means of said oneportion is constructed for slight leakage through said check valve meansduring inward strokes.

References Cited UNITED STATES PATENTS 1,855,064 4/ 1932 Messier.2,726,773 12/1955 Fitzjohn 213-43 3,147,826I 9/ 1964 McHenry 18S-883,252,587 5/ 1966 Scales 213-43 3,341,189 9/1967 Rumsey 213-43 X DRAYTONE. HOFFMAN, Primary Examiner U.S. Cl. X.R.

